chapter 6: microbial growth and nutrition Flashcards
How do microbes grow?
they grow in population not size
colony
aggregation of cells arising from CFU
CFU
colony forming unit
What do cells require for metabolism?
a carbon source, a source of energy, and a source of electrons and hydrogen
autotrophs
use inorganic sources as the sole source of carbon, make organic compounds from CO2
heterotrophs
catabolize reduced organic molecules that they acquire from other organisms
photons
contain lots of energy
phototrophs
use light as an energy source
chemotrophs
acquire energy from redox reactions
redox reactions
reduction and oxidation
nitrification
fixes atmospheric nitrogen
What is the common element in all cells?
hydrogen
organotrophs
acquire electrons from organic molecules
lithotrophs
acquire electrons and hydrogen from inorganic sources
obligate aerobes
need oxygen to live
clostridium tetani
anaerobe that produces tetanus
clostridium botilinum
botox
What are the 4 types of toxic oxygen?
singlet oxygen, superoxide radical, peroxide anion, and hydroxyl radical
carotenoids
pigments in phototropic microorganisms that prevents toxicity by removing excess energy from singlet oxygen
superoxide radicals
very reactive and toxic to aerobes that must use superoxide dismutase enzymes to detox them
Why are anaerobes sensitive to oxygen?
they lack superoxide dismutase
Which type of toxic oxygen is a very reactive oxidizing agent?
singlet oxygen
facultative anaerobes
-Aerobes that can maintain life by fermentation or anaerobic respiration
- Have a reduced metabolic efficiency
aerotolerant anaerobes
Dont use aerobic metabolism but can tolerate oxygen because of detoxifying enzymes
microaerophiles
Require oxygen in levels from 2%-10%
It can be damaged at higher oxygen levels
All the bacteria in a test tube are gathered at the top. What organism is this?
obligate aerobes
All the bacteria in a test tube is gathered at the bottom. What organism is this?
obligate anerobes
All the bacteria in a test tube are mostly at the top. What organism is this?
facultative anaerobes
All the bacteria are dispersed throughout. What organism is this?
aerotolerant anaerobes
nitrogen
often the growth limiting nutrient for many organisms
nitrogen fixation
reduction of nitrogen gas to ammonia and an essential process for life on earth
trace elements
other elements required in small amounts
growth factors
organic chemicals that most organisms cannot synthesize
ruminants
animals with rumen, a stomach sac with microflora
microflora
helps to digest cellulose
What are the 4 cow stomachs?
rumen, reticulum, omasum, abomasum
What happens to proteins at high temps?
they denature and hydrogen bonds break
minimum growth temp
lowest temp an organism can conduct metabolism
maximum growth temp
the highest temp at which an organism can metabolize
optimum growth temp
the temp at which an organisms metabolic activity is at the highest
physchrophiles
0-20
mesophiles
37 C
thermophiles
70 C
hyperthermophiles
120 C
neutrophiles
live in pH range of 6.5-7.5
acidophiles
grow best in acidic habitats
alkalinophiles
live in alkaline soils and water
antagonistic relationships
one organisms harms or kills the other
synergistic relationships
each member receives a benefit that exceeds that of what they’d have on their own
symbiotic relationships
organisms that live in contact so well that they depend on one another and rarely live outside the relationship
biofilm
complex community of bacteria living together
What are the benefits of the polymeric matrix of biofilm?
it can sequester substances in the film and protect the biofilm from antimicrobial drugs or the host’s immune response
qurom sensing
bacteria responds to the density of nearby bacteria and molecules to communicate with other bacteria
What happens if biofilms communicate?
it can cause cystic fibrosis, kidney infections
binary fission
cell grows to twice its size and divides in half to produce two daughter cells of equal size
generation time
the time required for a bacterial cell to grow and divide
arithmetic growth
simple addition,
exponential growth
2n
lag phase
cells adjust to their environment and prepare to divide
log phase
rapid reproduction once necessary chemicals have been synthesized
stationary phase
nutrients are used up, wastes accumulate, reproduction decreases, stays the same
death
cells die faster than they are produced
When would it be beneficial to use viable plate counts?
when the number of bacteria is too much
membrane filtration
when you have few bacteria and lots of solution
